This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The objective of this trial is to evaluate the safety, immunogenicity and clinical benefit of VCL-CB01 administered intramuscularly in HCT donors and recipients. The trial injection schedules for donors and recipients were selected after consideration of the limited availability of the donor, constrained timing of the transplant procedure, Phase I immunogenicity data and previous experience with licensed vaccines in transplant donors and recipients.